US2126793A - Removing fluorides from water - Google Patents
Removing fluorides from water Download PDFInfo
- Publication number
- US2126793A US2126793A US174203A US17420337A US2126793A US 2126793 A US2126793 A US 2126793A US 174203 A US174203 A US 174203A US 17420337 A US17420337 A US 17420337A US 2126793 A US2126793 A US 2126793A
- Authority
- US
- United States
- Prior art keywords
- water
- fluorides
- fluorine
- orthophosphoric acid
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title description 94
- 150000002222 fluorine compounds Chemical class 0.000 title description 26
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 44
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 26
- 229910052731 fluorine Inorganic materials 0.000 description 26
- 239000011737 fluorine Substances 0.000 description 26
- 235000011007 phosphoric acid Nutrition 0.000 description 22
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 13
- 239000000376 reactant Substances 0.000 description 12
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 11
- 239000000920 calcium hydroxide Substances 0.000 description 11
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 11
- 238000000034 method Methods 0.000 description 11
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 11
- 230000001988 toxicity Effects 0.000 description 7
- 231100000419 toxicity Toxicity 0.000 description 7
- 239000000463 material Substances 0.000 description 3
- 239000011343 solid material Substances 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 229940077441 fluorapatite Drugs 0.000 description 2
- 229910052587 fluorapatite Inorganic materials 0.000 description 2
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 208000002925 dental caries Diseases 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000036244 malformation Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
- C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
- C02F2101/14—Fluorine or fluorine-containing compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S210/00—Liquid purification or separation
- Y10S210/902—Materials removed
- Y10S210/915—Fluorine containing
Definitions
- This invention relates to the art of water purification, particularly the removal of dissolved fluorides from water.
- One of the objects of this invention is to remove fluorides or to reduce the fluorine content of water containing the same in solution, to an amount which is below the limit of toxicity for the fluorides in water.
- Another object of this invention is to provide a convenient and rapid method for removing or reducing the fluorides in water in order that it may be rendered potable.
- Other objects of this invention include the pro vision of a method for the economicalremoval or reduction of fluorides contained in water solutions.
- the water was acidified with 190 p. p. m. of orthophosphoric acid.
- 271 p. p. m. of calcium hydroxide were added to the uniform acidified water and the mixture maintained in an agitated condition for a period of 15 minutes, which, under the condi- 5 tions, was sufficient to form tricalcium orthophosphate from the reactants and to reduce the fluorine content of the water to 0.5 p. p. m.
- Water containing dissolved fluorides may or 15 may not contain suspended matter.
- the time required for the contact of the product of the reactants with the water is of the order of 15 to 30 minutes. Where no suspended matter is present, this time of contact under otherwise identical conditions, and as observed in a limited number of cases, is of the order of 10 hours. This time, however, may be materially reduced by the use of an amount of reactants in considerable excess of that otherwise required. It is therefore, necessary, when removing the solute fluoride from water, which is free of suspended matter, to add some suspended matter in order that the removal of the fluorine content of the water may be expedited.
- This may be accomplished by such means as the addition of finely divided argillaceous material to the water, or by adding to the water a reagent, or reagents, which produce finely divided suspended matter in the water, either for the sole purpose of providing the necessary suspended matter, or for the purpose of treating the water to remove other undesirable constituents.
- a reagent, or reagents which produce finely divided suspended matter in the water, either for the sole purpose of providing the necessary suspended matter, or for the purpose of treating the water to remove other undesirable constituents.
- aluminum sulfate with the subsequent product of a floc of aluminum hydroxide is an example of suitable material for accomplishing this result.
- the orthophosphoric acid used may be of any suitable commercial concentration. It is preferable to use a commercial orthophosphoric acid free from fluorine. However, should the specific circumstances require the use of an orthophosphoric acid containing fluorine, the amount of fluorine which it contains must be taken into account in addition to the amount of fluorine in the water, insofar as the requirements of orthophosphoric acid and calcium hydroxide are concerned, in calculating the amount of the respective reactants required. 5
- the amount of calcium hydroxide used is at least equivalent to that required to form tricalcium orthophosphate from the orthophosphoric acid used. Under these conditions the treated 5 water resulting will be at least neutral and generally slightly alkaline.
- Process of removing dissolved fluorides from water, tree from suspended matter, to render it potable which comprises adding at least 200 40 p. p. m. 01 suspended matter to the water; adding 30 to 40 p. p. m. of orthophosphoric acid to the water containing the suspended matter, for each p. p. m.
- Process of removing dissolved fluorides from water to render it potable which comprises add- ;5 ing 30 to 40 p. p. m. of orthophosphoric acid to the water, for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidifled water in an amount suiflcient to convert the orthophosphoric acid to tricalcium a0 orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is at least reduced below the limit of toxicity for the fluorides in the water; and separat- 5 ing the water from the residual solid material with which it has been contacted.
- Process of removing dissolved fluorides from water to render it potable which comprises adding at least 30 p. p. m. of orthophosphoric acid 70 to the water for each p. p. m. or fluorine contained in the water; adding calcium hydroxide to the acidifled water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content 01' the water is at least reduced below the limit of toxicity for the fluorides in the water; and separating the water from the residual solid material with which it has been contacted.
- Process of removing dissolved fluorides from water which comprises adding at least 30 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount sufllcient to convert the orthophosphoric acid to tricalcium orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is reduced below the desired limit for fluorine in the water; and separating the water from the residual solid material with which it has been contacted.
- Process of removing dissolved fluorides from water, free from suspended matter, to render it potable which comprises forming at least 200 p. p. m. of suspended matter in the water; adding 30 to 40 p. p. m. of orthophosphoric acid to the water containing the suspended matter, for
- Process of removing dissolved fluorides from water to render it potable which comprises adding 30 to 40 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is at least reduced below the limit 01' toxicity for the fluorides in water.
- Process of removing dissolved fluorides from water to render it potable which comprises adding at least 30 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorinecontained in the water; adding calcium hydroxide to the acidified water in an amount sufllcient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content oi the water is at least reduced below the limit of toxicity for the fluorides in water.
- Process of removing dissolved fluorides from water which comprises adding at least 30 p. p. m. 01' orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is reduced below the desired limit for fluorine in the water.
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Removal Of Specific Substances (AREA)
Description
Patented Aug. 16, 1938 No Drawing.
PATENT OFFICE 7 2,126,793 REMOVING FLUORIDES FROM WATER.
Walter H. Maclntire, Knoxville, Tenn.
8 Claims.
Application November 12, 1937, Serial No. 174,203
(Granted under the act of March a, 1883, as
amended April 30, 1928; 370 0. G. 757) The invention herein described may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.
This invention relates to the art of water purification, particularly the removal of dissolved fluorides from water.
One of the objects of this invention is to remove fluorides or to reduce the fluorine content of water containing the same in solution, to an amount which is below the limit of toxicity for the fluorides in water.
Another object of this invention is to provide a convenient and rapid method for removing or reducing the fluorides in water in order that it may be rendered potable. Other objects of this invention include the pro vision of a method for the economicalremoval or reduction of fluorides contained in water solutions.
There are numerous areas in the United States in which the water available for general consumption contains a considerable quantity of dissolved fluoride or fluorides with the amount of such dissolved fluorides corresponding to 5 to parts per million of fluorine.
It has been found that water containing fluoride corresponding to only 6 parts per million of fluorine results in the universal mottling of the enamel at the time of acquiring permanent teeth which results in premature tooth decay. It is now considered that water containing fluorides less than the equivalent to 1 to 2 parts per million of fluorine is below the limit of toxicity as evidenced by this particular type of malformation.
The generic invention and three specific adaptations are described and claimed in my copending application, Serial No. 164,139,,fl1ed September 16, 1937. and claimed in this application.
Another adaptation is described fluorine in the water.
One example of the operation of my process is given for the treatment of water containing 6 p. p. m. of dissolved fluorine and carrying 250 p. p. m. of suspended material.
The water was acidified with 190 p. p. m. of orthophosphoric acid. 271 p. p. m. of calcium hydroxide were added to the uniform acidified water and the mixture maintained in an agitated condition for a period of 15 minutes, which, under the condi- 5 tions, was sufficient to form tricalcium orthophosphate from the reactants and to reduce the fluorine content of the water to 0.5 p. p. m.
It is evident that there are numerous factors which will influence conditions for the most satl0 isfactory operation of my invention, the actual limits'of which cannot be established except by a detailed study of each set of raw materials and the finish-ed product involved.
Water containing dissolved fluorides may or 15 may not contain suspended matter. With the amount of suspended matter of the order of 200 p. p. m. and upward, the time required for the contact of the product of the reactants with the water is of the order of 15 to 30 minutes. Where no suspended matter is present, this time of contact under otherwise identical conditions, and as observed in a limited number of cases, is of the order of 10 hours. This time, however, may be materially reduced by the use of an amount of reactants in considerable excess of that otherwise required. It is therefore, necessary, when removing the solute fluoride from water, which is free of suspended matter, to add some suspended matter in order that the removal of the fluorine content of the water may be expedited. This may be accomplished by such means as the addition of finely divided argillaceous material to the water, or by adding to the water a reagent, or reagents, which produce finely divided suspended matter in the water, either for the sole purpose of providing the necessary suspended matter, or for the purpose of treating the water to remove other undesirable constituents. The use of aluminum sulfate with the subsequent product of a floc of aluminum hydroxide is an example of suitable material for accomplishing this result.
The orthophosphoric acid used may be of any suitable commercial concentration. It is preferable to use a commercial orthophosphoric acid free from fluorine. However, should the specific circumstances require the use of an orthophosphoric acid containing fluorine, the amount of fluorine which it contains must be taken into account in addition to the amount of fluorine in the water, insofar as the requirements of orthophosphoric acid and calcium hydroxide are concerned, in calculating the amount of the respective reactants required. 5
The amount of calcium hydroxide used is at least equivalent to that required to form tricalcium orthophosphate from the orthophosphoric acid used. Under these conditions the treated 5 water resulting will be at least neutral and generally slightly alkaline.
The results of experimental work over a peri 01' several years has led me to believe that the removal of soluble fluorides from water is accomplished largely by the formation 0! fluorapatite from the tricalcium crthophosphate and the fluoride in the water. The ratio of fluorine to tricalcium orthophosphate required to form fluorapatite is 1:245. In order to obtain eflective 15 removal of fluorine from water containing solute fluorides, it is necessary to have present at least double the amount of tricalcium orthophosphate theoretically required. Therefore, the minimum requirement for the amount of orthophosphoric 2o acid used is in the order of 30 to 40 p. p. m. for
' each p. p. m. of fluorine contained in the water.
In the treatment of considerable quantities of water, it is more feasible to carry out this treatment at the prevailing atmospheric temperature.
25 A number of experiments carried out over a period of several years has demonstrated the fact that the removal of fluorine from water containing solute fluorides is materially accelerated by the use oi moderately elevated temperatures.
30 It will be seen, therefore, that this invention actually may be carried out by the use of various modifications and changes without departing from its spirit and scope, with only such limitations placed thereon as are imposed by the prior 35 art.
I claim:
1. Process of removing dissolved fluorides from water, tree from suspended matter, to render it potable, which comprises adding at least 200 40 p. p. m. 01 suspended matter to the water; adding 30 to 40 p. p. m. of orthophosphoric acid to the water containing the suspended matter, for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidifled water n an amount sufllcient to convert the orthophosphoric acid to tricalcium orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is at least re- 50 duced below the limit of toxicity i'orthe fluorides in the water; and settling out the suspended matter from the water.
2. Process of removing dissolved fluorides from water to render it potable, which comprises add- ;5 ing 30 to 40 p. p. m. of orthophosphoric acid to the water, for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidifled water in an amount suiflcient to convert the orthophosphoric acid to tricalcium a0 orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is at least reduced below the limit of toxicity for the fluorides in the water; and separat- 5 ing the water from the residual solid material with which it has been contacted.
3. Process of removing dissolved fluorides from water to render it potable, which comprises adding at least 30 p. p. m. of orthophosphoric acid 70 to the water for each p. p. m. or fluorine contained in the water; adding calcium hydroxide to the acidifled water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content 01' the water is at least reduced below the limit of toxicity for the fluorides in the water; and separating the water from the residual solid material with which it has been contacted.
4. Process of removing dissolved fluorides from water, which comprises adding at least 30 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount sufllcient to convert the orthophosphoric acid to tricalcium orthophosphate; maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is reduced below the desired limit for fluorine in the water; and separating the water from the residual solid material with which it has been contacted.
5. Process of removing dissolved fluorides from water, free from suspended matter, to render it potable, which comprises forming at least 200 p. p. m. of suspended matter in the water; adding 30 to 40 p. p. m. of orthophosphoric acid to the water containing the suspended matter, for
each 1). p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is reduced below the desired limit for fluorine in the water.
6. Process of removing dissolved fluorides from water to render it potable, which comprises adding 30 to 40 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is at least reduced below the limit 01' toxicity for the fluorides in water.
'7. Process of removing dissolved fluorides from water to render it potable, which comprises adding at least 30 p. p. m. of orthophosphoric acid to the water for each p. p. m. of fluorinecontained in the water; adding calcium hydroxide to the acidified water in an amount sufllcient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content oi the water is at least reduced below the limit of toxicity for the fluorides in water.
8. Process of removing dissolved fluorides from water, which comprises adding at least 30 p. p. m. 01' orthophosphoric acid to the water for each p. p. m. of fluorine contained in the water; adding calcium hydroxide to the acidified water in an amount suflicient to convert the orthophosphoric acid to tricalcium orthophosphate; and maintaining the time of contact between the product of the reactants and the water such that the solute fluoride content of the water is reduced below the desired limit for fluorine in the water.
WALTER H. MACINTIRE.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US174203A US2126793A (en) | 1937-11-12 | 1937-11-12 | Removing fluorides from water |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US174203A US2126793A (en) | 1937-11-12 | 1937-11-12 | Removing fluorides from water |
Publications (1)
Publication Number | Publication Date |
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US2126793A true US2126793A (en) | 1938-08-16 |
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ID=22635257
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US174203A Expired - Lifetime US2126793A (en) | 1937-11-12 | 1937-11-12 | Removing fluorides from water |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2417462A (en) * | 1938-08-24 | 1947-03-18 | Victor Chemical Works | Treatment of tricalcium phosphate for improving fluorine adsorptiveness |
US2914474A (en) * | 1954-07-29 | 1959-11-24 | Phillips Petroleum Co | Removal of fluorides from industrial waste waters |
US3027304A (en) * | 1958-01-08 | 1962-03-27 | Aerial Products Inc | Process for fluoridating water |
-
1937
- 1937-11-12 US US174203A patent/US2126793A/en not_active Expired - Lifetime
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2417462A (en) * | 1938-08-24 | 1947-03-18 | Victor Chemical Works | Treatment of tricalcium phosphate for improving fluorine adsorptiveness |
US2914474A (en) * | 1954-07-29 | 1959-11-24 | Phillips Petroleum Co | Removal of fluorides from industrial waste waters |
US3027304A (en) * | 1958-01-08 | 1962-03-27 | Aerial Products Inc | Process for fluoridating water |
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